Re: [PATCH 2/3] USB: serial: digi_acceleport: fix incomplete rx sanity check

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On Tue, Jan 31, 2017 at 05:55:17PM +0100, Greg Kroah-Hartman wrote:
> On Tue, Jan 31, 2017 at 05:46:02PM +0100, Johan Hovold wrote:
> > On Tue, Jan 31, 2017 at 05:41:52PM +0100, Greg Kroah-Hartman wrote:
> > > On Tue, Jan 31, 2017 at 05:17:28PM +0100, Johan Hovold wrote:
> > > > Make sure the received data has the required headers before parsing it.
> > > > 
> > > > Also drop the redundant urb-status check, which has already been handled
> > > > by the caller.
> > > > 
> > > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> > > > Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
> > > > ---
> > > >  drivers/usb/serial/digi_acceleport.c | 38 ++++++++++++++++++++++--------------
> > > >  1 file changed, 23 insertions(+), 15 deletions(-)
> > > > 
> > > > diff --git a/drivers/usb/serial/digi_acceleport.c b/drivers/usb/serial/digi_acceleport.c
> > > > index 3b610f1e3f7c..eb433922598c 100644
> > > > --- a/drivers/usb/serial/digi_acceleport.c
> > > > +++ b/drivers/usb/serial/digi_acceleport.c
> > > > @@ -1398,25 +1398,30 @@ static int digi_read_inb_callback(struct urb *urb)
> > > >  {
> > > >  	struct usb_serial_port *port = urb->context;
> > > >  	struct digi_port *priv = usb_get_serial_port_data(port);
> > > > -	int opcode = ((unsigned char *)urb->transfer_buffer)[0];
> > > > -	int len = ((unsigned char *)urb->transfer_buffer)[1];
> > > > -	int port_status = ((unsigned char *)urb->transfer_buffer)[2];
> > > > -	unsigned char *data = ((unsigned char *)urb->transfer_buffer) + 3;
> > > > +	unsigned char *buf = urb->transfer_buffer;
> > > > +	int opcode;
> > > > +	int len;
> > > > +	int port_status;
> > > > +	unsigned char *data;
> > > >  	int flag, throttled;
> > > > -	int status = urb->status;
> > > > -
> > > > -	/* do not process callbacks on closed ports */
> > > > -	/* but do continue the read chain */
> > > > -	if (urb->status == -ENOENT)
> > > > -		return 0;
> > > >  
> > > >  	/* short/multiple packet check */
> > > > +	if (urb->actual_length < 2) {
> > > > +		dev_warn(&port->dev, "short packet received\n");
> > > > +		return -1;
> > > 
> > > Again, real error number?  -EINVAL?  -EIO?
> > > 
> > > > +	}
> > > > +
> > > > +	opcode = buf[0];
> > > > +	len = buf[1];
> > > > +
> > > >  	if (urb->actual_length != len + 2) {
> > > > -		dev_err(&port->dev, "%s: INCOMPLETE OR MULTIPLE PACKET, "
> > > > -			"status=%d, port=%d, opcode=%d, len=%d, "
> > > > -			"actual_length=%d, status=%d\n", __func__, status,
> > > > -			priv->dp_port_num, opcode, len, urb->actual_length,
> > > > -			port_status);
> > > > +		dev_err(&port->dev, "malformed packet received: port=%d, opcode=%d, len=%d, actual_length=%u\n",
> > > > +			priv->dp_port_num, opcode, len, urb->actual_length);
> > > > +		return -1;
> > > 
> > > Same here and elsewhere in this patch.
> > 
> > As the OOB function in the previous patch, this one is also documented
> > as returning -1 on sanity-check failures so I'm not changing that
> > behaviour now.
> > 
> > Also note that the return value is only checked against zero and never
> > used for anything else currently.
> 
> Ok, nevermind, my fault.
> 
> Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

Thanks for reviewing these. Applying for -next.

Johan
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